Many infinitely variable transmission (IVT) machines have over the years been proposed and developed in attempts to produce, from a constant input velocity, an acceptable linear continuously variable output angular velocity and torque.
The basic approach to these machines has been initially to apply a single input angular velocity to a number of parallel stages of the machines which by means of angular velocity generators such as cams, slotted plates, linkages, off-centred sun gears, non-circular gears, orbital devices, universal joints and so on produced pulsed or cycled angular velocities (angular acceleration and deceleration cycles) in each of the stages which are appropriately phased to the input angular velocity. The pulsed or cycled angular velocities from the machine stages are then used to drive selective extraction devices, such as overrunning or sprag clutches and/or differentials which extract the maximum portions of the driven cycles of the parallel stages to provide modulated angular velocity outputs. These outputs are then recombined in an output stage of the machine to provide the output angular velocity of the machine. Examples of these machines are disclosed in the specifications of the following publications: WO82/02233, WO89/11604, WO90/01648, WO91/18225, WO94/11652, WO02/14715, FR916850A, U.S. Pat. No. 1,916,283A, U.S. Pat. No. 3,114,273, BE444789A and FR1071870A
Common problems which are typically associated with IVT machines of the prior art are that:
they are capable of transmitting power in only one direction of rotation, which cannot be reversed,
their cyclic angular velocity generating devices generate, in each parallel stage of the machine, a full cycle of a periodic motion on each revolution of their input shafts with their single drive direction overrunning clutch extraction devices being capable of clipping only the single maximum velocity peak from each cycle. The consequence of this is that the angular velocity output arrangements of the machines, such as planetary gear systems, are largely incapable of fully modulating the coarsely rippled output of the extraction devices to an acceptable purely or nearly so theoretically constant linear output velocity. The majority of the cyclic angular velocity generating devices which are employed in the IVT machines, and which include oscillating components such as the slotted plates, linkages which drive or are driven by off-centre gears, cams and the like suffer from balancing and other vibration problems which are principally caused mainly by shock loads generated by the direction changing mechanisms. The above are complex machines not suitable for practical implementation with the necessary level of reliability.